Prior art workers have devised many types of pressing machines. The present invention is directed to that type of pressing machine having a stationary buck and a head shiftable between an open position and a closed position against the buck.
In the usual prior art pressing operation, the fabric workpiece to be pressed is located on the buck and the head of the press is lowered to its closed position, but applies zero pressure to the buck and the workpiece. Steam is introduced into the workpiece via the head or the buck to soften the workpiece and render it manageable. Thereafter, the head is returned to its normal open position and the workpiece is manually smoothed and rendered wrinkle free. At this point, the head is again returned to its closed position against the buck, and is locked under high pressure for a "dwell time" of from about 5 seconds to about 10 seconds. Thereafter, the head is returned to its normal open position and the vacuum valve in association with the buck is opened to cause ambient air to be drawn through the workpiece and the buck to dry the workpiece. The drying step of the pressing cycle generally takes in the neighborhood of from about 17 to about 18 seconds.
The present invention is based upon the discovery that if a cowling is located above and sealed to the steam chamber of the head, and if the cowling is provided at one end with air intake holes and near the other end with a valve which, when open, connects the cowling directly with the spray chamber of the head, and if the head is provided with a peripheral resilient sealing means forming a seal with a peripheral rim on the buck when the head is in its closed, zero pressure position, a number of advantages are achieved. The drying step is conducted with the head in its closed, sealed, zero-pressure position. The air valve of the cowling is opened and the vacuum valve of the buck is also opened. This results in preheated ambient air, having been in heat exchange with the head steam chamber while traveling through the cowling, to be drawn through the workpiece to dry the workpiece. It has been found that this procedure saves air conditioning and prevents air conditioned air from being drawn through the workpiece and creating wet spots therein. Vacuum time is saved and better pressing results The drying step of the pressing cycle is reduced to about 5 seconds, greatly increasing the productivity of the fabric pressing machine.
It has further been found that a longitudinal seam in the workpiece (and particularly a lapped seam as will be described hereinafter) is sharper and straighter if tension is applied to the workpiece, transversely of the seam, during the pressing operation.
As is known in the art, the buck is surmounted by an assembly comprising a grid plate, a pad and a cover of ironing board cloth or drill cloth. In accordance with the present invention, the assembly of the grid plate, pad and cover is split longitudinally to form a front half assembly and a rear half assembly. In one embodiment, the front half assembly is fixed to the buck and the rear half assembly is shiftable on the buck toward and away from the front half assembly. In this way, tension can be applied to the workpiece during the pressing operation.
In another embodiment, both halves of the buck assemblies are shiftable toward and away from each other. In addition, the head of the pressing machine is split longitudinally into two halves, shiftable toward and away from each other by a predetermined distance. Such split heads are known in the art. In this instance, when the head is closed upon the workpiece and the buck, separation of the head halves can result in a similar separation of the buck assembly halves, again applying tension to the workpiece, perpendicular to a longitudinal seam therein.